Courtney Dressing

Exoplanets

I am currently working with David Charbonneau to investigate the occurrence rate of small planets around M dwarfs. We recently used multi-band photometry to improve the radius and temperature estimates of the smallest stars in the Kepler target list and revised the radii of the associated planet candidates. We found that the occurrence rate of 0.5-4 Earth radius planets with periods < 50 days is 0.90 (+0.04/-0.03) planets per small star and that the occurrence rate of 0.5-1.4 Earth radius planets in the habitable zones of small stars is 0.04 planets per star. This implies that the nearest Earth-size planet in the habitable zone of a small star is within 5 pc at 95% confidence. Please see Dressing & Charbonneau, 2013, ApJ, 767, 95 for more details.

One of the challenges of detecting transiting exoplanets is that several astrophysical phenomena can masquerade as transiting planets. High resolution adaptive optics images can help distinguish between real transiting planets and astrophysical false positives by revealing the presence of nearby stars. In collaboration with Andrea Dupree and Elisabeth Adams, I acquired high-resolution adaptive optics images of Kepler target stars using ARIES at the MMT. For our sample of 87 targets, we identified visual companions within 1'' for five stars, between 1'' and 2'' for seven stars, and between 2'' and 4'' for 15 stars. We estimated dilution corrections for the radii of the planet candidates in those systems under the assumption that they orbit the target star. We also placed limits on the presence of undetected stars. Our typical limits were 5.3 Ks magnitudes fainter than the target star within 1'' and 5.7 Ks magnitudes fainter within 2''. The details are explained in Dressing, Adams, & Dupree et al. 2014, AJ, 148, 78.

For my undergraduate senior thesis at Princeton University, I worked with Ed Turner,
Michael McElwain, and the
SEEDS (Strategic Explorations of Exoplanets and Disks with Subaru)
collaboration to directly image young Jovian exoplanets using the Subaru telescope. The SEEDS project aims to discover young planets in order to improve
our knowledge of planet formation and migration. For more information about the SEEDS project and results of our survey of members of stellar moving groups please see Brandt et al. 2014, ApJ, 786, 1.